Women graduates keep flocking to the big City law firms. They make up about 60% of their trainee intake, having accounted for approximately half of those entering this branch of the profession for well over a decade. It's pretty shocking, then, that just 18% of these firms' partners are female.

Some attribute this to subtle factors – for example, appraisals featuring criteria such as "gravitas" which implicitly favour men, or social events geared to golf or traditionally male pastimes such as golf. But while these things may be demotivating, putting too much focus on them risks ignoring the long, antisocial hours City lawyers are required to work. Many regularly do 70-80 hour weeks. For female partners with families that often means rushing home from the office to put the kids to bed, then working until the early hours of the morning to meet billing targets.

The next generation of women lawyers is not overly keen to embrace such a routine. A female associate in her early 30s who is on the verge of quitting her magic circle law firm told me recently: "I look at the women partners here, most of whom are from the shoulder-pad-wearing 80s generation of women who thought they could have it all, and I just think how much I don't want to be like them."

This attitude worries the big law firms because it means they are losing talented people and, in many instances, having to promote less talented people in their place. Operating like this makes them feel dysfunctional, and dysfunctional tends to be bad for business. So they have acted by bringing in a host of part-time working initiatives.

To date, these schemes have failed to catch on, with only single-digit percentages of partners signing up. The most recent venture, a programme by Allen & Overy allowing its equity partners to work reduced hours, was launched amid great optimism earlier this year but has so far yielded only 15 participants. (The firm has 355 equity partners, 46 of whom are women.) Speaking off the record, many lawyers say that while the thinking behind these schemes is well-meaning, participating in them amounts to "career suicide".

So where next? The obvious next step is concrete targets to increase female representation at partner level, fostering a culture where working fewer hours is more acceptable. So far only two firms, Addleshaw Goddard and Clifford Chance, have done this, setting targets of 25% and 30% respectively. Most of their rivals are against such an approach, arguing that it breaches meritocratic principles – an odd assertion to make given that the current situation facing female lawyers is highly unmeritocratic. How sustainable this counter-intuitive stance proves in the long term will depend on demographic variables that are difficult to predict, but logic suggests that as the population ages and people retire later it will make even less sense for organisations to lose so many women early in their careers.

Dr Louise Ashley, a Cass business school fellow whose research focuses on diversity in professional services organisations, describes City law firms' public spiel on gender as "characterised by platitudes to the point where it's almost become dishonest". No wonder young female lawyers feel cynical. Meaningless platitudes will surely have to give way to meaningful actions, but knowing City law firms – and their notorious aversion to change – the process will drag on for a few years yet.